High-wear-resistance and high-corrosion-resistance ultra-coarse grain hard alloy as well as preparation method and application thereof

Abstract

The invention discloses a high-wear-resistance and high-corrosion-resistance ultra-coarse grain hard alloy and a preparation method and application thereof, and belongs to the technical field of hard alloys. The hard alloy provided by the invention is prepared from the following raw materials in percentage by mass: 10-30% of Co; 10%-30% of Ni; 1 to 6 percent of AlN; 0.2 to 3 percent of VC (Vinyl Chloride); 0.2% to 3% of Mo2C; 0.5 to 5 percent of Cr3C2; 0.5 to 5 percent of TaC; 0.5 to 5 percent of NbC; the balance is WC; and the average grain size of WC is 5-15 [mu] m. The obtained hard alloy binding phase is in a continuous network coating WC crystal grains, and contains fine gamma'phase precipitates; a small amount of added carbide forms a dispersed secondary phase ((Ta, W) C, (Nb, W) C and the like) or is dissolved in a matrix, and an eta phase with remarkable brittleness does not appear, so that the compatibility of high hardness and high toughness of the alloy is ensured, and meanwhile, the alloy has good wear resistance and corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of cemented carbide, and in particular to a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, a preparation method thereof, and applications thereof. Background Art

[0002] The information disclosed in the background of the invention is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Cemented carbide is a composite material made from refractory metal carbides (such as tungsten carbide and titanium carbide) and metal binders (such as cobalt, nickel, and iron) through a powder metallurgy process. It exhibits excellent properties such as high hardness, high wear resistance, high strength, high temperature resistance, and corrosion resistance. Its performance is primarily determined by the refractory metal carbide grain size and the metal binder content. Ultra-coarse-grained cemented carbide, with its coarse grains and well-developed crystal structure, effectively reduces the driving force of crack propagation and the mismatch in its unloading process, significantly improving its toughness. It is widely used in deep mining tools such as oil and gas drilling, mineral mining, and tunneling.

[0004] Although metallic Co exhibits excellent wettability and adhesion to tungsten carbide (WC), making it an optimal binder for cemented carbide, it exhibits significant drawbacks under harsh operating conditions. These issues, such as preferential wear, high-temperature oxidation, and poor corrosion resistance, have become significant factors limiting the service life of ultra-coarse-grained cemented carbide in major deep-ground mining projects. Therefore, there is an urgent need to strengthen Co-based binders to comprehensively enhance the overall performance of ultra-coarse-grained cemented carbide for deep-ground mining applications. To address this issue, researchers have attempted to improve the binder's wear and corrosion resistance to some extent by introducing trace elements such as Cr, Ni, and Mo for solid solution strengthening. However, this approach has significant limitations: It is difficult to achieve a balanced balance of mechanical properties, wear resistance, and corrosion resistance in cemented carbide using trace element additions alone. For example, while excessive Ni addition improves the alloy's corrosion resistance, it reduces the Ni binder's wettability on WC, leading to a decrease in alloy strength. Therefore, developing an ultra-coarse-grained cemented carbide with high wear resistance, corrosion resistance, and mechanical properties suitable for deep-ground mining applications is an urgent task. Summary of the Invention

[0005] In view of this, the present invention provides a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, and a preparation method and application thereof. The ultra-coarse-grained cemented carbide provided by the present invention adds Ni, AlN, transition metal carbides, etc. to the WC-Co ultra-coarse-grained cemented carbide, and precipitates an ordered structured nano-reinforced phase in the ultra-coarse-grained cemented carbide Co-based binder, so that the alloy effectively improves the hardness and wear resistance of the binder, and significantly improves the corrosion resistance of the alloy.

[0006] In a first aspect, the present invention provides a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, which is made from the following raw materials in percentage by mass: Co: 10~30%; Ni: 10~30%; AlN: 1~6%; VC: 0.2~3%; Mo2C: 0.2~3%; Cr3C2: 0.5~5%; TaC: 0.5~5%; NbC: 0.5~5%; the balance is WC; The average grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 5-15 μm.

[0007] Preferably, the wear-resistant and highly corrosion-resistant ultra-coarse-grained cemented carbide is made of the following raw materials in percentage by mass: Co: 10~15%; Ni: 10~15%; AlN: 2~5%; VC: 0.3~1%; Mo2C: 0.3~1%; Cr3C2: 1~3%; TaC: 1~3%; NbC: 1~3%; the balance is WC; The average grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 8-14 μm.

[0008] In a second aspect, the present invention provides a method for preparing the above-mentioned highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, comprising the following steps: WC powder, Co powder, Ni powder, AlN powder, VC powder, Mo2C powder, Cr3C2 powder, TaC powder and NbC powder are wet ball-milled into slurry, spray granulated and then formed into green compacts, and the green compacts are sintered and cooled to obtain the product.

[0009] Preferably, the slurry contains a binder and a dispersant, the content of the binder is 1-3 wt %, and the content of the dispersant is 0.1-0.5 wt %.

[0010] Furthermore, the binder is polyvinyl alcohol, and the dispersant is ammonium polyacrylate.

[0011] Preferably, in the spray granulation step, the temperature of the drying chamber is 170-220°C, and the air outlet temperature is 90-100°C.

[0012] Preferably, the sintering process is: S1. Heat the sample to 200-250°C at a rate of 4-8°C / min, then heat the sample to 380-420°C at a rate of 0.5-1.5°C / min. S2, then raise the temperature to 1200-1250°C at a heating rate of 4-8°C / min and keep the temperature constant for 40-80min; S3. Then, heat the temperature to 1400-1500°C at a heating rate of 4-8°C / min and keep the temperature constant for 40-80 minutes.

[0013] Furthermore, 130-170 mbar inert gas is introduced into the S1 and S2 stages, and 40-60 mbar inert gas is introduced into the S3 stage.

[0014] Preferably, the cooling is furnace cooling to room temperature.

[0015] In a third aspect, the present invention provides the use of the above-mentioned highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide or the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide prepared by the above-mentioned preparation method in the field of deep mining tools.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) The highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide provided by the present invention constructs a synergistic optimization system of Co-Ni-Al binder and WC-based hard phase (containing carbides) by limiting the proportion of each component and controlling the average grain size of WC; wherein, the Co-Ni-Al binder phase provides the component basis for the precipitation of the γ′ strengthening phase ((Ni, Co)3Al) during sintering and cooling, forming a γ / γ′ dual-phase structure similar to that of high-temperature alloys to enhance the mechanical properties and heat resistance of the binder phase; the addition of multiple carbides is to coordinate the growth of WC grains, form a protective oxide film and improve the corrosion resistance. Through the design of specific composition and ratio, the cemented carbide binder phase obtained by the present invention presents a continuous network coating WC grains and contains fine γ′ phase precipitates; a small amount of added carbides forms a dispersed secondary phase (such as cubic phases such as (Ta, W)C and (Nb, W)C) or is solid dissolved in the matrix, and no significant brittle η phase appears, thereby ensuring the compatibility of high hardness and high toughness of the alloy, while also having good wear resistance and corrosion resistance.

[0017] (2) This invention reduces material costs by partially replacing Co with Ni (Ni content 10-30%). Furthermore, performance is improved by adding trace amounts of low-cost carbides (such as VC and Cr3C2), which is more economical than increasing the precious metal content or using complex coatings. Furthermore, the preparation process follows the conventional powder metallurgy route (wet ball milling, spray granulation, and sintering), requiring no special equipment and showing promising prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute undue limitations thereon. It is obvious that one of ordinary skill in the art could derive other drawings based on these drawings without inventive effort.

[0019] Figure 1 Schematic diagram of the sintering system of Example 1 of the present invention.

[0020] Figure 2 1 is a scanning electron microscope image of the sample of Example 1 of the present invention. DETAILED DESCRIPTION

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0022] Explanation of terms: γ phase: FCC (face-centered cubic crystal structure) solid solution mainly formed by Co, Ni and Al.

[0023] γ' phase: refers to the L12 type ordered strengthening phase (such as (Ni, Co)3Al) precipitated in the binder alloy, which can significantly improve the strength of the binder phase.

[0024] η phase: A carbon-deficient phase formed in the alloy due to insufficient carbon content (decarburization), belonging to M6C or M 12 C-type carbides, such as Co3W3C phase, are significantly brittle and are malignant defects in alloy structures.

[0025] Passivation film: A dense oxide layer formed on the surface of a material in a corrosive environment, which reduces the corrosion rate by hindering ion diffusion and charge transfer.

[0026] Corrosion current density: A kinetic parameter that reflects the redox reaction rate on the surface of a material and can more directly measure the corrosion resistance of the material.

[0027] Galvanic corrosion: refers to the localized corrosion phenomenon in which when phases with different potentials (such as WC hard phase and Co / Ni-based binder phase) come into contact in a corrosive medium or are connected through an electronic conductor, a corrosion galvanic cell is formed due to the potential difference, resulting in accelerated corrosion of the phase with a more negative potential (such as the binder phase) and slower corrosion of the phase with a more positive potential (such as WC).

[0028] Steady-state friction coefficient: The steady-state friction coefficient is the average value of the friction coefficient when it reaches a relatively stable state after the initial running-in period. This parameter reflects the actual friction characteristics of the material during long-term use and is a key indicator for evaluating the material's wear resistance and energy loss.

[0029] The present invention provides a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, which is made from the following raw materials in percentage by mass: Co: 10~30%; Ni: 10~30%; AlN: 1~6%; VC: 0.2~3%; Mo2C: 0.2~3%; Cr3C2: 0.5~5%; TaC: 0.5~5%; NbC: 0.5~5%; the balance is WC; The average grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 5-15 μm.

[0030] Cobalt (Co) metal, with its excellent wettability on WC, is the core of traditional binders. The addition of Ni to form a Co-Ni composite binder reduces dependence on scarce Co resources (cost and resource advantages). Ni's superior corrosion resistance (Ni is more stable in acidic and alkaline media) also enhances the overall corrosion resistance of the binder phase. The two elements synergistically provide the compositional foundation for the subsequent precipitation of the γ′-strengthening phase ((Ni, Co)3Al). During sintering, AlN decomposes, and Al reacts with Ni to form a dispersed γ′ phase ((Ni, Co)3Al), creating a γ / γ′ dual-phase structure similar to that of high-temperature alloys. As a hard intermetallic compound, the γ′ phase significantly enhances the strength, heat resistance, and corrosion resistance of the binder phase through precipitation strengthening (inhibiting preferential dissolution of the binder phase).

[0031] Trace amounts of Mo in Mo2C dissolve into the matrix or form secondary phases, improving the alloy's electrochemical stability (reducing corrosion current density) and inhibiting galvanic corrosion in chloride solutions. Cr and V partially dissolve into the binder phase and migrate to the surface during corrosion, forming a dense passivation film that isolates the corrosive medium and reduces the potential difference between WC and the binder phase, thereby reducing the tendency to galvanic corrosion. Ta and Nb form cubic solid solutions of (Ta,W)C and (Nb,W)C with WC, increasing the hardness of the hard phase. As a hard phase, ultra-coarse-grained WC (5-15μm) itself can reduce the driving force for crack growth (improving toughness).

[0032] In the present invention, the wear-resistant and highly corrosion-resistant ultra-coarse-grained cemented carbide is made of the following raw materials in percentage by mass: Co: 10~15%; Ni: 10~15%; AlN: 2~5%; VC: 0.3~1%; Mo2C: 0.3~1%; Cr3C2: 1~3%; TaC: 1~3%; NbC: 1~3%; the balance is WC; The grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 8-14 μm.

[0033] For example, in different embodiments, the content of Co may be 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, etc.; The Ni content can be 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, etc. The content of AlN can be 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.; The VC content can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc. The content of Mo2C can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc. The content of Cr3C2 can be 1.2%, 1.5%, 1.8%, 2.2%, 2.5%, 2.8%, etc. The TaC content can be 1.2%, 1.5%, 1.8%, 2.2%, 2.5%, 2.8%, etc.

[0034] The NbC content can be 1.2%, 1.5%, 1.8%, 2.2%, 2.5%, 2.8%, etc.

[0035] The present invention also provides a method for preparing the above-mentioned highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, comprising the following steps: WC powder, Co powder, Ni powder, AlN powder, VC powder, Mo2C powder, Cr3C2 powder, TaC powder and NbC powder are wet ball-milled into slurry, spray granulated and then formed into green compacts, and the green compacts are sintered and cooled to obtain the product.

[0036] The wet ball milling process is not particularly limited in this invention; commonly used wet ball milling procedures can be employed. The preferred milling medium is water-ethanol (liquid-to-solid ratio ≥ 2:1). This prevents powder oxidation (ethanol's reducing properties) while also improving mixing uniformity through the liquid's "lubricating" effect (avoiding agglomeration during dry milling). YG8 carbide balls are used for the milling process, with a ball-to-material ratio of 4-8:1, a rotation speed of 100-300 rpm, and a duration of 5-20 hours. YG8 balls are highly hard (wear-resistant) and contaminant-resistant. The ball-to-material ratio and rotation speed control milling efficiency. Prolonged milling results in the in-situ formation of a nano-carbide coating on the WC surface, inhibiting abnormal grain growth during subsequent sintering.

[0037] In the present invention, the slurry contains a binder and a dispersant, the content of the binder is 1 to 3 wt%, and the content of the dispersant is 0.1 to 0.5 wt%. Furthermore, the binder is polyvinyl alcohol, which wraps the powder particles through intermolecular forces, improves the strength and fluidity of the particles after granulation, and avoids fragmentation during molding. The dispersant is ammonium polyacrylate, which prevents the particles from agglomerating in the slurry through electrostatic repulsion or steric hindrance effects, ensuring that the droplets are uniform during spray granulation. In order to ensure that the binder and dispersant are evenly distributed in the slurry, stirring is also required, and the solid content of the final slurry is greater than 80 wt%.

[0038] In the present invention, in the spray granulation step, the temperature of the drying chamber is 170~220℃, and the air outlet temperature is 90~100℃; the high temperature quickly evaporates the surface moisture of the droplets (forming a hard shell), and the low temperature prevents the internal moisture from evaporating violently and causing the particles to crack (the temperature difference between the inside and the outside is small). The present invention does not impose any special restrictions on other parameters of spray drying, and the conventional settings in this field can be adopted. The preferred atomizer speed of the present invention is: 15000~20000 rpm. Feed pump speed: controlled at 5~10 mL / min to ensure uniform atomized particles. Air flow velocity: adjusted to 1.5~2.0 m 3 / min, ensuring that the particles are fully suspended and dried in the drying chamber. The particle size D50 of spray granulation is 80-120μm. The spherical particles have good fluidity, which is conducive to filling the mold during molding or cold isostatic pressing (reducing porosity). At the same time, the uniform particle size ensures consistent green density.

[0039] The present invention further comprises the steps of crushing, screening, and drying after spray granulation. Screening is performed to remove large particles and agglomerates and to ensure the size and uniformity of the particles. The present invention does not impose any particular restrictions on the mesh size of the screening sieve, and preferably, 50 to 200 mesh is used. The present invention does not impose any particular restrictions on the specific drying method and time, and preferably, vacuum drying is used.

[0040] The present invention does not impose any special restrictions on the specific forming and blanking process. For samples with simple shapes, compression molding is used. For example, a green body is obtained by cold pressing at a pressure of 200-300 MPa in a steel mold for more than 3 minutes (compression molding uses secondary pressurization, that is, pressurization for 2-5 minutes, then pressure relief, and then re-pressurization for 2-5 minutes to increase density). Cold isostatic pressing at a pressure of 300 MPa (time ≥ 3 minutes) can also be used, which will result in better green body density and uniformity.

[0041] In the present invention, the sintering process is: S1. Raise the temperature to 200-250°C at a rate of 4-8°C / min, then to 380-420°C at a rate of 0.5-1.5°C / min. Raise the temperature slowly to remove residual binder (PVA decomposition) and adsorbed water, and avoid rapid heating that causes gas expansion (cracking of the green body). S2. Then, heat the temperature to 1200-1250°C at a heating rate of 4-8°C / min and maintain the temperature for 40-80 minutes. The medium temperature stage promotes the decomposition of AlN (releasing Al and N), while some low-melting-point components (such as Co and Ni) begin to form a liquid phase (wetting the WC particles). Maintaining the temperature ensures uniform diffusion of the components.

[0042] S3. Then heat the steel to 1400-1500°C at a heating rate of 4-8°C / min and keep the temperature constant for 40-80min. During the high temperature stage, WC dissolves and reprecipitates in the liquid phase (promoting densification), and at the same time, γ′ phase ((Ni, Co)3Al) begins to precipitate.

[0043] In the present invention, 130-170 mbar inert gas (such as N2, Ar, etc.) is introduced in the S1 and S2 stages to maintain the furnace atmosphere and prevent oxidation; 40-60 mbar inert gas (such as N2, Ar, etc.) is introduced in the S3 stage to suppress Co volatilization (maintain the binder phase content).

[0044] The present invention does not impose any particular limitation on the cooling process. It is preferably cooled to room temperature during the furnace cooling to ensure that the γ′ phase is fully dispersed and precipitated (avoiding rapid cooling that causes coarse or uneven precipitation phases) while reducing thermal stress (preventing alloy cracking).

[0045] The present invention also provides the use of the above-mentioned high-wear-resistant and high-corrosion-resistant ultra-coarse-grained cemented carbide or the high-wear-resistant and high-corrosion-resistant ultra-coarse-grained cemented carbide prepared by the above-mentioned preparation method in the field of deep mining tools.

[0046] Deep mining tools (such as oil and gas drill bits, mining tools) need to withstand high impact loads, strong wear (rock / sand friction), corrosion (containing Cl - The high wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide of the present invention meets the requirements through the following characteristics: High corrosion resistance: γ′ phase increases the corrosion resistance of the binder phase. The ultra-coarse WC grains have good toughness and are basically not corroded (the traditional WC-Co alloy causes the hard phase to fall off due to the dissolution of the binder phase), which extends the life in the mud environment.

[0047] High hardness and toughness synergy: HRA85~88.5 hardness resists abrasive cutting, and 2700~3200MPa bending strength withstands impact loads (coarse-grained WC reduces the driving force for crack propagation + γ′ phase strengthens the bearing capacity of the bonding phase).

[0048] Excellent wear resistance: γ′ phase strengthens the bonding phase + carbide enhances the hardness of the hard phase, combined with the protection of the Mo oxide film during the friction process, the steady-state friction coefficient is below 0.6.

[0049] Cost and resource advantages: Ni replaces part of Co (Ni is cheaper and has abundant reserves) + conventional powder metallurgy process (no special equipment required), reducing tool manufacturing and maintenance costs and improving the feasibility of industrial application.

[0050] The technical solution of the present invention is further described below with reference to specific examples. The present invention has no particular limitation on the sources of the reagents used in the following examples, and commercially available products known to those skilled in the art can be used.

[0051] Example 1 This embodiment provides a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide and a preparation method thereof.

[0052] The high wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide of this embodiment is composed of the following raw materials in percentage by mass: Co: 12%; Ni: 12%; AlN: 2.5%; VC: 0.5%; Mo2C: 0.5%; Cr3C2: 1.5%; TaC: 1.5%; NbC: 1.5%; the balance is WC.

[0053] The preparation method is as follows: (1) Mixing: The powders of each component were weighed and mixed uniformly according to the proportions. Wet milling was performed using a planetary ball mill with anhydrous ethanol as the medium (liquid-to-solid ratio = 3:1) to prevent powder oxidation and improve mixing uniformity. YG8 carbide balls were added to the milling container as the grinding medium, and the ball-to-material ratio was controlled to be approximately 5:1. The milling speed was approximately 200 rpm for 10 hours to ensure that the components were fully mixed and a nano-carbide coating was formed in situ on the surface of the WC grains to prevent agglomeration.

[0054] (2) Slurry preparation: 2 wt% polyvinyl alcohol (PVA) was added to the ball-milled slurry as a binder to increase particle strength and improve fluidity. 0.2 wt% ammonium polyacrylate was added as a dispersant to prevent the slurry from agglomerating during spraying. The mixture was stirred evenly at 300 rpm for 30 minutes to ensure uniform distribution of the binder and dispersant. The final slurry had a solid content greater than 80 wt%.

[0055] (3) Spray granulation: Start the spray dryer, preheat the drying chamber to 200°C, and control the air outlet temperature at 100°C to avoid cracking caused by a large temperature difference between the inside and outside of the particles. Atomizer speed: 18,000 rpm. Feed pump speed: 8 mL / min to ensure uniform atomized particles. Air flow rate: 1.5 m³ / min to ensure that the particles are fully suspended and dried in the drying chamber. The final product is spherical particles with a particle size distribution of D50 ≈ 100 μm.

[0056] (4) Screening: Crush the agglomerated mixed powder and sieve it through a 100-mesh sieve to ensure the size and uniformity of the particles.

[0057] (5) Drying: Place the prepared particles in a vacuum drying oven at 80°C and dry for 2 hours.

[0058] (6) Molding: The green body is formed by compression molding, cold pressing at a pressure of 300 MPa in a steel mold for 3 minutes, releasing the pressure, and then re-pressurizing for 3 minutes to obtain a green body.

[0059] (7) Sintering process (see the sintering system diagram Figure 1 The green body was placed in a sintering furnace for densification. After evacuating the furnace and introducing 150 mbar nitrogen (to maintain nitrogen balance within the sintered body), the temperature was raised to 220°C at a rate of 5°C / min, then to 400°C at a rate of 1°C / min to remove residual binder and impurities. Then, the temperature was raised to 1230°C and held for 60 minutes under 150 mbar nitrogen to fully decompose the AlN. The body was then raised to 1470°C and held for 60 minutes to form a gradient layer. During this sintering period, 50 mbar argon was introduced to suppress Co volatilization, allowing the WC hard phase to fully dissolve, partially forming a liquid phase in the binder phase and then reprecipitating, promoting microstructure densification. The specific sintering schedule is shown in Table 1. After sintering and holding, the body was slowly cooled to ≤200°C in a furnace-cooled manner before being removed from the furnace. During cooling, Ni and Al in the binder phase gradually precipitated to form a dispersed γ′ strengthening phase.

[0060] like Figure 2 As shown in the figure, the average size of the ultra-coarse-grained cemented carbide grains in this embodiment is 8.6μm, no abnormally grown grains are observed, and no significantly brittle η phase appears; γ′ phase particles with a size of about 150nm are distributed in the binder phase, realizing precipitation strengthening of the binder phase; additives such as VC and Cr3C2 are dissolved in the binder phase, improving the corrosion resistance of the binder phase; elements such as Mo, Ta, and Nb form a cubic phase solid solution, improving the hardness of the hard phase.

[0061] Table 1 Sintering system of this example

[0062] Example 2 The difference between this embodiment and embodiment 1 is that the high wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide of this embodiment is composed of the following raw materials in terms of mass percentage: Co: 12%; Ni: 12%; AlN: 2%; VC: 0.5%; Mo2C: 0.5%; Cr3C2: 1.8%; TaC: 1.8%; NbC: 1%; the balance is WC.

[0063] The preparation method is the same as that of Example 1.

[0064] Example 3 The difference between this embodiment and embodiment 1 is that the high wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide of this embodiment is composed of the following raw materials in terms of mass percentage: Co: 10%; Ni: 10%; AlN: 2%; VC: 0.8%; Mo2C: 0.8%; Cr3C2: 1.5%; TaC: 1.5%; NbC: 1.5%; the balance is WC.

[0065] The preparation method is the same as that of Example 1.

[0066] Example 4 The difference between this embodiment and embodiment 1 is that the high wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide of this embodiment is composed of the following raw materials in terms of mass percentage: Co: 15%; Ni: 15%; AlN: 5%; VC: 0.8%; Mo2C: 0.8%; Cr3C2: 1.5%; TaC: 1.5%; NbC: 1.5%; the balance is WC.

[0067] The preparation method is the same as that of Example 1.

[0068] Comparative Example 1 The only difference between this comparative example and Example 1 is that, in this comparative example, VC: 1.5%; Mo2C: 1.5%; Cr3C2: 0.5%; TaC: 0.5%; and NbC: 0.5%.

[0069] Comparative Example 2 The only difference between this comparative example and Example 1 is that this comparative example does not contain Cr3C2, and the missing part is supplemented by VC, Mo2C, TaC and NbC. Specifically, VC: 0.7%; Mo2C: 0.7%; TaC: 2.05%; NbC: 2.05%.

[0070] Comparative Example 3 Compared with Example 1, the only difference between this comparative example and Example 1 is that this comparative example does not contain TaC, and the missing part is supplemented by VC, Mo2C, Cr3C2 and NbC. Specifically, VC: 0.7%; Mo2C: 0.7%; Cr3C2: 2.05%; NbC: 2.05%.

[0071] Comparative Example 4 The only difference between this comparative example and Example 1 is that this comparative example does not contain AlN.

[0072] Co: 12%; Ni: 12%; VC: 0.5%; Mo2C: 0.5%; Cr3C2: 1.5%; TaC: 1.5%; NbC: 1.5%; the balance is WC.

[0073] Test example The properties of the cemented carbides of Examples 1 to 4 and Comparative Examples 1 to 4 were measured, and the test results are shown in Table 2.

[0074] The Vickers hardness (HV) scale is used to evaluate the hardness of cemented carbide. During the test, a load of 10 kg is maintained for 15 seconds. Each sample is tested three or more times, and the average value is taken as the final hardness result.

[0075] The flexural strength was determined using the three-point bending method. Sample dimensions were 5.25 mm × 6.5 mm × 20 mm (span 14.5 mm) and the loading rate was 1 mm / min. Five specimens were selected from each component sample, and the strength values were averaged.

[0076] The friction and wear properties of cemented carbide were evaluated using a reciprocating sliding dry friction and wear test method with a ball-plane contact. The friction pair used a 6mm Si3N4 ball, with a set load of 20N, a reciprocating friction distance of 5mm, a friction time of 30min, and a motor speed of 200r / min.

[0077] The corrosion performance of cemented carbide was evaluated using a conventional three-electrode configuration electrochemical corrosion method. SCE The potential polarization test was carried out at a scan rate of 1 mV / s in the potential range, and the corrosion current density was obtained by extrapolating the Tafel curve.

[0078] Table 2 Results of cemented carbide performance measurements of Examples 1 to 4 and Comparative Examples 1 to 4

[0079] From the above test data, it can be seen that the average WC grain size of the material of the embodiment of the present invention is 8-12 μm, and it can also maintain high strength, toughness, friction, wear and corrosion resistance.

[0080] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide, characterized in that: Made from the following raw materials in percentage by mass: Co: 10~30%; Ni: 10~30%; AlN: 1~6%; VC: 0.2~3%; Mo2C: 0.2~3%; Cr3C2: 0.5~5%; TaC: 0.5~5%; NbC: 0.5~5%; the balance is WC; The average grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 5-15 μm.

2. The highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide according to claim 1, characterized in that: The wear-resistant and highly corrosion-resistant ultra-coarse-grained cemented carbide is made of the following raw materials in percentage by mass: Co: 10~15%; Ni: 10~15%; AlN: 2~5%; VC: 0.3~1%; Mo2C: 0.3~1%; Cr3C2: 1~3%; TaC: 1~3%; NbC: 1~3%; the balance is WC; The average grain size of WC in the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide is 8-14 μm.

3. The method for preparing a highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide according to any one of claims 1 to 2, characterized in that: The steps include: WC powder, Co powder, Ni powder, AlN powder, VC powder, Mo2C powder, Cr3C2 powder, TaC powder and NbC powder are wet ball-milled into slurry, spray granulated and then formed into green compacts, and the green compacts are sintered and cooled to obtain the product.

4. The preparation method according to claim 3, wherein The slurry contains a binder and a dispersant, wherein the content of the binder is 1-3 wt %, and the content of the dispersant is 0.1-0.5 wt %.

5. The preparation method according to claim 4, wherein The binder is polyvinyl alcohol, and the dispersant is ammonium polyacrylate.

6. The preparation method according to claim 3, wherein In the spray granulation step, the temperature of the drying chamber is 170-220°C, and the air outlet temperature is 90-100°C.

7. The preparation method according to claim 3, wherein The sintering process is: S1. Heat the sample to 200-250°C at a rate of 4-8°C / min, then heat the sample to 380-420°C at a rate of 0.5-1.5°C / min. S2, then raise the temperature to 1200-1250°C at a heating rate of 4-8°C / min and keep the temperature constant for 40-80min; S3. Then, heat the temperature to 1400-1500°C at a heating rate of 4-8°C / min and keep the temperature constant for 40-80 minutes.

8. The preparation method according to claim 7, wherein Inert gas at 130-170 mbar is introduced into the S1 and S2 stages, and inert gas at 40-60 mbar is introduced into the S3 stage.

9. The preparation method according to claim 3, wherein The cooling is furnace cooling to room temperature.

10. Use of the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide according to any one of claims 1 to 2 or the highly wear-resistant and corrosion-resistant ultra-coarse-grained cemented carbide prepared by the preparation method according to any one of claims 3 to 9 in the field of deep mining tools.

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