NbC lattice skeleton dominant type low-carbon tungsten carbide hard alloy and preparation method and application thereof

Abstract

The application discloses a NbC lattice skeleton dominant type low-carbon tungsten hard alloy and a preparation method and application thereof, and belongs to the field of advanced powder metallurgy technology. The NbC lattice skeleton dominant type low-carbon tungsten hard alloy is prepared from the following raw materials, wherein the raw materials comprise hard phase raw materials, binder phase raw materials and an adjusting agent; the hard phase raw materials comprise niobium carbide and tungsten carbide; the niobium carbide accounts for 82-96 wt% of the total mass of the hard phase raw materials, and the C / Nb atomic ratio of the niobium carbide is 0.96-1.04; the tungsten carbide accounts for 4-18% of the total mass of the hard phase raw materials; the binder phase raw materials comprise polyborosilazane / boron phosphate hybrid network precursor and Co-Ni binary alloy; and the adjusting agent comprises a Cr3C2 / Mo2C mixture, a magnesium-aluminum bimetallic hydroxide / Si3N4 composite and borazine modified boron nitride nanofiber. In the application, NbC is used to replace WC as the main skeleton, so that the good matching of hardness and toughness is realized without sacrificing the hardness, and the application is suitable for the application of seawater corrosion-resistant parts and has good seawater corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of advanced powder metallurgy technology, and relates to an NbC lattice framework-dominant low-carbide tungsten carbide, its preparation method and application. Background Technology

[0002] Cemented carbide is a composite material composed of refractory metal carbides (such as WC, TiC, NbC, etc.) and a metallic binder phase (such as Co, Ni, Fe, etc.). It has high hardness and high wear resistance and is widely used in cutting tools, mining tools and wear-resistant parts.

[0003] WC cemented carbide is the preferred material for equipment used in marine environments due to its excellent wear resistance. However, traditional WC cemented carbide often fails to fully meet the material requirements of such equipment, and tungsten resources are currently under strategic shortage. WC-Co cemented carbide, with Co as the binder phase, has high hardness and is one of the most mature cemented carbide systems, but it has poor corrosion resistance. WC-Ni cemented carbide, with Ni as the binder phase, has excellent corrosion resistance, but its mechanical properties are relatively poor. Summary of the Invention

[0004] The purpose of this invention is to provide an NbC lattice framework-dominant low-carbide tungsten carbide, its preparation method, and its application, which solves the problem that traditional WC tungsten carbide cannot meet the material requirements of equipment operating in marine environments.

[0005] The technical solution adopted in this invention is as follows:

[0006] A low-carbide tungsten carbide cemented carbide dominated by an NbC lattice framework is prepared by the following raw materials, which include hard phase raw materials, binder phase raw materials, and modifiers;

[0007] The hard phase raw materials include niobium carbide and tungsten carbide; niobium carbide accounts for 82-96 wt% of the total mass of the hard phase raw materials, and the C / Nb atomic ratio of niobium carbide is 0.96-1.04; tungsten carbide accounts for 4-18% of the total mass of the hard phase raw materials.

[0008] The binder phase raw materials include a polyboron silazane / boron phosphate hybrid network precursor and a Co-Ni binary alloy;

[0009] The regulators include a Cr3C2 / Mo2C mixture, a magnesium-aluminum bimetallic hydroxide / Si3N4 complex, and borazine-modified boron nitride nanofibers.

[0010] Further, the polyborosilicate / boron phosphate hybrid network precursor is prepared by the following method: The polyborosilicate precursor is dissolved in xylene to prepare a polyborosilicate precursor solution with a mass concentration of 15%~25%; boron phosphate is added to the polyborosilicate precursor solution, the amount of boron phosphate added being 2%~2.5% of the mass of the polyborosilicate precursor, and after ultrasonic dispersion, a uniform dispersion is obtained; under a nitrogen or argon atmosphere, triethylamine / 4-dimethylaminopyridine dual catalyst is added to the dispersion, and the reaction is stirred at 60°C for 3~4 hours. After the reaction is completed, the mixture is distilled under reduced pressure to obtain the polyborosilicate / boron phosphate hybrid network precursor; wherein the amount of triethylamine added is 2 wt% of the mass of the polyborosilicate precursor, and the amount of 4-dimethylaminopyridine added is 1 wt% of the mass of the polyborosilicate precursor.

[0011] The amount of the polyborosilazane / boron phosphate hybrid network precursor added is 10% of the total mass of the hard phase feedstock.

[0012] Furthermore, the mass ratio of Co to Ni in the Co-Ni binary alloy is 1:1; the amount of Co-Ni binary alloy added is 3wt% of the total mass of the hard phase raw materials.

[0013] Furthermore, the mass ratio of Cr3C2 to Mo2C in the Cr3C2 / Mo2C mixture is 2:1; the amount of Cr3C2 / Mo2C mixture added is 0.25% of the total mass of the hard phase raw material and the binder phase raw material.

[0014] Further, the magnesium-aluminum bimetallic hydroxide / Si3N4 composite was prepared by the following method: magnesium nitrate and aluminum nitrate were dissolved in deionized water at a Mg:Al molar ratio of 2:1 to prepare a mixed salt solution with a concentration of 0.5 mol / L; the mixed salt solution was added dropwise to an ethanol suspension of Si3N4 under stirring; after the addition was completed, dilute ammonia was added dropwise to the reaction system to adjust the pH to 9.5; the reaction was carried out at 60°C for 12 hours; after the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the magnesium-aluminum bimetallic hydroxide / Si3N4 composite.

[0015] The amount of magnesium-aluminum bimetallic hydroxide / Si3N4 composite added is 1% of the total mass of the hard phase raw material and the binder phase raw material.

[0016] Further, the borazine-modified boron nitride nanofibers are prepared by the following method: boron nitride nanofibers are placed in a low-temperature oxygen plasma treatment device and treated for 5 minutes under an oxygen atmosphere and a power of 200 W to obtain pretreated boron nitride nanofibers; under an inert atmosphere, the pretreated boron nitride nanofibers, borazine, and triethylamine are added to a reaction vessel and sealed for reaction, with borazine accounting for 30 wt% of the mass of the pretreated boron nitride nanofibers and triethylamine accounting for 2 wt% of the mass of the pretreated boron nitride nanofibers; under the sealed state of the vessel, ultrasonic treatment is carried out at 35-45℃ for 30 minutes, followed by heating to 50℃ and holding for 3-4 hours, after the reaction is completed, the temperature is raised to 120℃ and stirred for 2-3 hours, after the reaction is completed, centrifugation is performed, the precipitate is collected, the precipitate is washed, vacuum dried, and then heat-treated at 200℃ for 2 hours under inert gas protection at a rate of 2-5℃ / min to obtain borazine-modified boron nitride nanofibers;

[0017] The amount of boron azazine-modified boron nitride nanofibers added is 1.2% of the total mass of the hard phase raw material and the binder phase raw material.

[0018] The method for preparing an NbC lattice framework-dominant low-carbide tungsten carbide includes the following steps:

[0019] S1. Niobium carbide and tungsten carbide are mixed evenly and placed in a radio frequency plasma treatment device. Surface activation treatment is carried out in an atmosphere of H2 and Ar with a volume ratio of 1:8. The radio frequency power is 300W and the treatment time is 30 minutes to obtain a hard phase raw material.

[0020] S2. Place the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture in a three-dimensional vibrating ball mill, add 1% stearic acid (1% of the total mass of the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture), with a ball-to-material ratio of 5:1 and a rotation speed of 150-200 rpm. Add magnesium-aluminum bimetallic hydroxide / Si3N4 composite 30 minutes before the end of ball milling, and ball mill for 8 hours. After ball milling, vacuum dry at 60℃ for 6 hours to obtain composite powder.

[0021] S3. Dissolve the polyborosilicate / boron phosphate hybrid network precursor in xylene to form a solution with a mass concentration of 15-25%. Under stirring, add the composite powder and boron azine-modified boron nitride nanofibers to the solution in sequence. After stirring evenly, a composite slurry is obtained.

[0022] S4. After vacuum drying of the composite slurry at 80-120℃, it is cold isostatically pressed at 200-300 MPa for 5-10 minutes to obtain the green body.

[0023] S5. Perform three-stage vacuum sintering on the green body:

[0024] First stage: Increase the temperature to 150-250℃ at a rate of 1-2℃ / min, hold for 60-120 minutes, and maintain a vacuum level better than 10. -2 Pa;

[0025] Second stage: After the first stage of heat preservation, increase the temperature to 1000-1150℃ at a rate of 2-4℃ / min, and maintain the temperature for 60-90 minutes, with a vacuum degree better than 10. -2 Pa;

[0026] Third stage: After the second stage of heat preservation, increase the temperature to 1300-1400℃ at a rate of 1-2℃ / min, and hold for 30-60 minutes, with a vacuum degree better than 10. -2 Pa;

[0027] S6. Post-treatment: After the third stage of sintering is completed, argon gas is introduced to increase the pressure to 80-150MPa within the temperature range of 1250-1350℃, and the pressure is maintained for 0.5-2 hours.

[0028] S7, Gradient Cooling

[0029] Rapid cooling section: After post-treatment, cool to 1000-1050℃ at 15-25℃ / min;

[0030] Medium-temperature insulation section: After rapid cooling, cool to 750-850 ℃ at 3-5 ℃ / min, and maintain the temperature for 20-40 min;

[0031] Slow cooling section: After holding at medium temperature, the material is cooled to room temperature at a rate of less than 2 °C / min to obtain a low-carbide tungsten carbide with an NbC lattice framework.

[0032] Furthermore, the aforementioned NbC lattice framework-dominant low-carbide tungsten carbide is used to prepare deep-sea wear-resistant and corrosion-resistant components.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] 1. This invention discloses an NbC lattice framework-dominated low-carbide tungsten carbide with NbC as the main framework, which reduces the amount of WC used compared to traditional WC tungsten carbide. In existing tungsten carbides, NbC is generally used as a trace or small amount of additive. Although it has high hardness, it has low fracture toughness, so it is rarely used as the main framework. This application uses NbC instead of WC as the main framework, and without sacrificing hardness, it combines NbC with polyborosilazane / boron phosphate hybrid network precursors, Co-Ni binary alloys, Cr3C2 / Mo2C mixtures, magnesium-aluminum bimetallic hydroxide / Si3N4 composites, and borazine-modified boron nitride nanofibers to effectively compensate for the insufficient fracture toughness caused by high NbC content, achieving a good match between hardness and toughness.

[0035] 2. In this invention, a Co-Ni binary alloy is used as one of the binder phase materials. During sintering, a polyborosilicate / boron phosphate hybrid network precursor undergoes pyrolysis and phase transformation, which segments and encapsulates the Co-Ni phase, physically blocking the corrosion current path and enhancing passivation. Furthermore, the solid products of the pyrolysis of the polyborosilicate / boron phosphate hybrid network precursor can fill gaps and pores, improving the density of the alloy matrix. This effectively reduces the penetration of water molecules, chloride ions, and acidic media into the hard alloy matrix. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0037] Figure 1 This is a flowchart illustrating the preparation method of the NbC lattice framework-dominated low-carbide tungsten carbide of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0040] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0041] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0042] This invention discloses an NbC lattice framework-dominant low-carbide tungsten carbide, which is prepared from the following raw materials, including hard phase raw materials, binder phase raw materials, and modifiers;

[0043] The hard phase raw materials include niobium carbide and tungsten carbide; niobium carbide accounts for 82-96 wt% of the total mass of the hard phase raw materials, and the C / Nb atomic ratio of niobium carbide is 0.96-1.04; tungsten carbide accounts for 4-18% of the total mass of the hard phase raw materials.

[0044] The binder phase raw materials include a polyboron silazane / boron phosphate hybrid network precursor and a Co-Ni binary alloy;

[0045] The regulators include a Cr3C2 / Mo2C mixture, a magnesium-aluminum bimetallic hydroxide / Si3N4 complex, and borazine-modified boron nitride nanofibers.

[0046] In the following embodiments, the polyborosilicate / boron phosphate hybrid network precursor was prepared by the following method: Polyborosilicate precursor was dissolved in xylene to prepare a polyborosilicate precursor solution with a mass concentration of 15%~25%; boron phosphate was added to the polyborosilicate precursor solution, the amount of boron phosphate added being 2%~2.5% of the mass of the polyborosilicate precursor; after ultrasonic dispersion, a uniform dispersion was obtained; under a nitrogen or argon atmosphere, triethylamine / 4-dimethylaminopyridine dual catalyst was added to the dispersion, and the reaction was stirred at 60°C for 3~4 hours; after the reaction was completed, the mixture was distilled under reduced pressure to obtain the polyborosilicate / boron phosphate hybrid network precursor; wherein the amount of triethylamine added was 2wt% of the mass of the polyborosilicate precursor, and the amount of 4-dimethylaminopyridine added was 1wt% of the mass of the polyborosilicate precursor.

[0047] The amount of the polyborosilazane / boron phosphate hybrid network precursor added is 10% of the total mass of the hard phase feedstock.

[0048] In the following embodiments, the mass ratio of Co to Ni in the Co-Ni binary alloy is 1:1; the amount of Co-Ni binary alloy added is 3wt% of the total mass of the hard phase raw materials.

[0049] In the following embodiments, the mass ratio of Cr3C2 to Mo2C in the Cr3C2 / Mo2C mixture is 2:1; the amount of Cr3C2 / Mo2C mixture added is 0.25% of the total mass of the hard phase raw material and the binder phase raw material.

[0050] In the following examples, the magnesium-aluminum bimetallic hydroxide / Si3N4 composite was prepared by the following method: magnesium nitrate and aluminum nitrate were dissolved in deionized water at a Mg:Al molar ratio of 2:1 to prepare a mixed salt solution with a concentration of 0.5 mol / L; the mixed salt solution was added dropwise to an ethanol suspension of Si3N4 under stirring; after the addition was completed, dilute ammonia was added dropwise to the reaction system to adjust the pH to 9.5; the reaction was carried out at 60°C for 12 hours; after the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the magnesium-aluminum bimetallic hydroxide / Si3N4 composite.

[0051] The amount of magnesium-aluminum bimetallic hydroxide / Si3N4 composite added is 1% of the total mass of the hard phase raw material and the binder phase raw material.

[0052] In the following embodiments, the borazine-modified boron nitride nanofibers were prepared by the following method: Boron nitride nanofibers were placed in a low-temperature oxygen plasma treatment device and treated for 5 minutes under an oxygen atmosphere and a power of 200 W to obtain pretreated boron nitride nanofibers; under an inert atmosphere, the pretreated boron nitride nanofibers, borazine, and triethylamine were added to a reaction vessel and sealed for reaction. The borazine accounted for 30 wt% of the mass of the pretreated boron nitride nanofibers, and the amount of triethylamine added was 2 wt% of the mass of the pretreated boron nitride nanofibers; under the sealed container, the mixture was ultrasonically treated at 35-45°C for 30 minutes, then heated to 50°C and held for 3-4 hours. After the reaction, the temperature was raised to 120°C and stirred for 2-3 hours. After the reaction, the mixture was centrifuged, the precipitate was collected, washed, vacuum dried, and then heat-treated at 200°C for 2 hours under inert gas protection at a rate of 2-5°C / min to obtain borazine-modified boron nitride nanofibers.

[0053] The amount of boron azazine-modified boron nitride nanofibers added is 1.2% of the total mass of the hard phase raw material and the binder phase raw material.

[0054] like Figure 1 As shown, the preparation method of the NbC lattice framework-dominated low-carbide tungsten carbide includes the following steps:

[0055] S1. Niobium carbide and tungsten carbide are mixed evenly and placed in a radio frequency plasma treatment device. Surface activation treatment is carried out in an atmosphere of H2 and Ar with a volume ratio of 1:8. The radio frequency power is 300W and the treatment time is 30 minutes to obtain a hard phase raw material.

[0056] S2. Place the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture in a three-dimensional vibrating ball mill, add 1% stearic acid (1% of the total mass of the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture), with a ball-to-material ratio of 5:1 and a rotation speed of 150-200 rpm. Add magnesium-aluminum bimetallic hydroxide / Si3N4 composite 30 minutes before the end of ball milling, and ball mill for 8 hours. After ball milling, vacuum dry at 60℃ for 6 hours to obtain composite powder.

[0057] S3. Dissolve the polyborosilicate / boron phosphate hybrid network precursor in xylene to form a solution with a mass concentration of 15-25%. Under stirring, add the composite powder and boron azine-modified boron nitride nanofibers to the solution in sequence. After stirring evenly, a composite slurry is obtained.

[0058] S4. After vacuum drying of the composite slurry at 80-120℃, it is cold isostatically pressed at 200-300 MPa for 5-10 minutes to obtain the green body.

[0059] S5. Perform three-stage vacuum sintering on the green body:

[0060] First stage: Increase the temperature to 150-250℃ at a rate of 1-2℃ / min, hold for 60-120 minutes, and maintain a vacuum level better than 10. -2 Pa;

[0061] Second stage: After the first stage of heat preservation, increase the temperature to 1000-1150℃ at a rate of 2-4℃ / min, and maintain the temperature for 60-90 minutes, with a vacuum degree better than 10. -2 Pa;

[0062] Third stage: After the second stage of heat preservation, increase the temperature to 1300-1400℃ at a rate of 1-2℃ / min, and hold for 30-60 minutes, with a vacuum degree better than 10. -2 Pa;

[0063] S6. Post-treatment: After the third stage of sintering is completed, argon gas is introduced to increase the pressure to 80-150MPa within the temperature range of 1250-1350℃, and the pressure is maintained for 0.5-2 hours.

[0064] S7, Gradient Cooling

[0065] Rapid cooling section: After post-treatment, cool to 1000-1050℃ at 15-25℃ / min;

[0066] Medium-temperature insulation section: After rapid cooling, cool to 750-850 ℃ at 3-5 ℃ / min, and maintain the temperature for 20-40 min;

[0067] Slow cooling section: After holding at medium temperature, the material is cooled to room temperature at a rate of less than 2 °C / min to obtain a low-carbide tungsten carbide with an NbC lattice framework.

[0068] In the following embodiments, the NbC lattice framework-dominant low-carbide tungsten carbide is used to prepare deep-sea wear-resistant and corrosion-resistant components.

[0069] The specific implementation method is as follows:

[0070] Example 1

[0071] A preferred embodiment of the present invention provides an NbC lattice framework-dominant low-carbide tungsten carbide, which is prepared by the following method:

[0072] 1. Raw material ratio

[0073] Hard phase raw materials: Niobium carbide (C / Nb atomic ratio of 1.00) accounts for 90 wt% of the total mass of hard phase raw materials, and tungsten carbide accounts for 10 wt% of the total mass of hard phase raw materials.

[0074] The binder phase raw materials consist of a polyborosilazane / boron phosphate hybrid network precursor accounting for 10 wt% of the total mass of the hard phase raw materials; and a Co-Ni binary alloy (Co:Ni mass ratio of 1:1) accounting for 3 wt% of the total mass of the hard phase raw materials.

[0075] Modifiers: Cr3C2 / Mo2C mixture (mass ratio 2:1) accounts for 0.25 wt% of the total mass of the hard phase raw material and the binder phase raw material; magnesium aluminum bimetallic hydroxide / Si3N4 composite accounts for 1 wt% of the total mass of the hard phase raw material and the binder phase raw material; borazine-modified boron nitride nanofibers account for 1.2 wt% of the total mass of the hard phase raw material and the binder phase raw material.

[0076] 2. Preparation of polyborosilazane / boron phosphate hybrid network precursors

[0077] 100 g of polyborosilicate precursor (number average molecular weight 2000 g / mol) was dissolved in 400 g of xylene, and 2.2 g of boron phosphate (80-120 nm particle size) was added. The mixture was ultrasonically dispersed for 30 minutes. Under nitrogen protection, 2 g of triethylamine and 1 g of DMAP were added, and the mixture was stirred at 60 °C for 3.5 hours. After the reaction was completed, the mixture was distilled under reduced pressure at 55 °C and 2 kPa to obtain the polyborosilicate / boron phosphate hybrid network precursor.

[0078] 3. Preparation of magnesium-aluminum bimetallic hydroxide / Si3N4 composite

[0079] Magnesium nitrate and aluminum nitrate were dissolved in deionized water at a molar ratio of Mg:Al = 2:1 to prepare 200 mL of a 0.5 mol / L mixed salt solution. This solution was added dropwise to an ethanol suspension containing 20 g of Si3N4 under stirring. The pH was adjusted to 9.5 by adding dilute ammonia, and the solution was crystallized at 60 °C for 12 hours. After centrifugation and washing, the solution was dried at 80 °C for 12 hours to obtain a magnesium-aluminum bimetallic hydroxide / Si3N4 composite.

[0080] 4. Preparation of boron azazine-modified boron nitride nanofibers

[0081] 10g of boron nitride nanofibers were placed in an oxygen plasma treatment device and treated for 5 minutes at an oxygen atmosphere and a power of 200 W. Under argon protection, the pretreated boron nitride nanofibers, 3g of borazine, and 0.2g of triethylamine were added to a sealed reaction vessel. The mixture was sonicated at 40℃ for 30 minutes, heated to 50℃ and held for 3.5 hours, and then heated to 120℃ and stirred for 2.5 hours. The mixture was centrifuged, washed three times with xylene, and dried under vacuum. Under argon protection, the mixture was heat-treated to 200℃ at a rate of 3℃ / min and held for 2 hours.

[0082] 5. Alloy preparation

[0083] S1. Niobium carbide and tungsten carbide are mixed evenly and placed in a radio frequency plasma treatment device. Surface activation treatment is carried out in an atmosphere of H2 and Ar with a volume ratio of 1:8. The radio frequency power is 300W and the treatment time is 30 minutes to obtain a hard phase raw material.

[0084] S2. The hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture were placed in a three-dimensional vibrating ball mill. Stearic acid at 1% of the total mass of the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture was added. The ball-to-material ratio was 5:1, the rotation speed was 200 rpm, and after ball milling for 7.5 hours, magnesium-aluminum bimetallic hydroxide / Si3N4 composite was added, and ball milling continued for 0.5 hours. After ball milling, the composite powder was vacuum dried at 60℃ for 6 hours to obtain the composite powder.

[0085] S3. Dissolve the polyborosilicate / boron phosphate hybrid network precursor in xylene to form a 20% (w / w) solution. Under stirring, add the composite powder and boron azine-modified boron nitride nanofibers to the solution in sequence. After stirring evenly, a composite slurry is obtained.

[0086] S4. The composite slurry is vacuum dried at 100℃ and then cold isostatically pressed at 250 MPa for 8 minutes to obtain the green body.

[0087] S5. Perform three-stage vacuum sintering on the green body:

[0088] First stage: Increase the temperature to 200℃ at a rate of 1℃ / min, hold for 90 minutes, and maintain a vacuum level better than 10. -2 Pa;

[0089] Second stage: After the first stage of heat preservation, the temperature is increased to 1100℃ at a rate of 3℃ / min, and maintained for 75 minutes, with a vacuum degree better than 10. -2 Pa;

[0090] Third stage: After the second stage of heat preservation, the temperature is increased to 1350℃ at a rate of 2℃ / min, and held for 45 min, with a vacuum degree better than 10. -2 Pa;

[0091] S6. Post-treatment: After the third stage of sintering is completed, argon gas is introduced at 1300℃ and pressurized to 120MPa, and the pressure is maintained for 1 hour.

[0092] S7, Gradient Cooling

[0093] Rapid cooling section: After post-treatment, cool to 1000℃ at 20℃ / min;

[0094] Medium-temperature insulation section: After rapid cooling, cool to 800℃ at 4℃ / min and hold for 30 min;

[0095] Slow cooling section: After holding at medium temperature, the material is cooled to room temperature at a cooling rate of 1.5 ℃ / min to obtain a low-carbide tungsten carbide with NbC lattice framework as the main type.

[0096] Example 2

[0097] This embodiment is based on Embodiment 1, but differs from Embodiment 1 in that the ratio of hard phase raw materials is different;

[0098] Niobium carbide accounts for 82 wt% of the total mass of the hard phase raw materials, and tungsten carbide accounts for 18 wt%. The proportions and preparation methods of the remaining raw materials are the same as in Example 1.

[0099] Example 3

[0100] This embodiment is based on Embodiment 1, but differs from Embodiment 1 in that the ratio of hard phase raw materials is different;

[0101] Niobium carbide accounts for 96 wt% of the total mass of the hard phase raw materials, and tungsten carbide accounts for 4 wt%. The proportions and preparation methods of the remaining raw materials are the same as in Example 1.

[0102] Comparative Example 1

[0103] Based on Example 1, the difference from Example 1 is that the binder phase in this comparative example is a single Co-Ni binary alloy, without the addition of a polyborosilicate / boron phosphate hybrid network precursor; the Co-Ni binary alloy accounts for 13 wt% of the total mass of the hard phase raw materials; the rest is the same as in Example 1.

[0104] Comparative Example 2

[0105] Based on Example 1, except that this comparative example does not contain the magnesium-aluminum bimetallic hydroxide / Si3N4 composite. Everything else is the same as in Example 1.

[0106] Comparative Example 3

[0107] Based on Example 1, except that borazine-modified boron nitride nanofibers were not added in this comparative example. Everything else is the same as in Example 1.

[0108] Comparative Example 4

[0109] Based on Example 1, the difference from Example 1 is that the binder phase material in this comparative example is a polyborosilazane precursor (number average molecular weight 2000 g / mol), accounting for 10 wt% of the total mass of the hard phase material; and a Co-Ni binary alloy (Co:Ni mass ratio of 1:1), accounting for 3 wt% of the total mass of the hard phase material. All other aspects are the same.

[0110] Blank Group 1

[0111] Based on Example 1, this blank group provides an NbC lattice framework-dominant low-carbide tungsten carbide, which is prepared by the following raw materials, including hard phase raw materials, binder phase raw materials, and modifiers;

[0112] The hard phase raw materials include niobium carbide and tungsten carbide; niobium carbide accounts for 90 wt% of the total mass of the hard phase raw materials, and the C / Nb atomic ratio of niobium carbide is 1; tungsten carbide accounts for 10% of the total mass of the hard phase raw materials.

[0113] The binder phase material is a Co-Ni binary alloy (Co:Ni mass ratio of 1:1), and the Co-Ni binary alloy accounts for 13 wt% of the total mass of the hard phase material.

[0114] The regulator is a Cr3C2 / Mo2C mixture, and the Cr3C2 / Mo2C mixture (Cr3C2 / Mo2 mass ratio 2:1) accounts for 0.25 wt% of the sum of the masses of the hard phase raw material and the binder phase raw material.

[0115] The preparation method is as described in Example 1. Niobium carbide and tungsten carbide are mixed uniformly and then treated in a radio frequency plasma treatment device. After treatment, they are ball-milled with a Co-Ni binary alloy and a Cr3C2 / Mo2C mixture in a three-dimensional vibrating ball mill. Following ball milling, the mixture is cold isostatically pressed, then sintered, post-treated, and subjected to gradient cooling. (Specific parameters are as described in Example 1.)

[0116] Blank Group 2

[0117] The cemented carbide used in this blank group is the existing cemented carbide WC-13Co.

[0118] Blank Group 3

[0119] The cemented carbide used in this blank group is the existing cemented carbide WC-13Ni.

[0120] Test case

[0121] Sample preparation

[0122] The cemented carbide samples from Examples 1-3, Comparative Examples 1-4, and Blank Groups 1-3 were machined into standard test specimens:

[0123] Hardness test specimen: 20 mm × 20 mm × 5 mm in size, with the test surface polished to a mirror finish using diamond polishing paste.

[0124] Fracture toughness test specimens: short rod specimens were fabricated according to ASTM B771 standard.

[0125] Corrosion sample: 10 mm × 10 mm × 3 mm in size. All surfaces were sanded with SiC sandpaper up to 1200#, polished to mirror finish, ultrasonically cleaned, and dried for later use.

[0126] Hardness testing: Refer to standard GB / T 3849.1-2015 (Hard alloy Rockwell hardness test (A scale) Part 1: Test method); Three sets of parallel specimens, expressed as mean ± standard deviation;

[0127] Fracture toughness testing: performed according to ASTM B771-11, "Standard Test Method for Fracture Toughness of Carbide Short Bars"; three sets of parallel specimens, expressed as mean ± standard deviation;

[0128] Corrosion detection: Simulated environment: 3.5 wt% NaCl aqueous solution, simulating deep-sea seawater environment, temperature 25℃; referring to GB / T 24196-2009, a three-electrode system was adopted (saturated calomel electrode as reference, platinum sheet as auxiliary, and sample as working electrode), the scanning rate of potentiodynamic polarization curve was 1 mV / s, and the detection indexes were self-corrosion potential (Ecorr) and corrosion current density (Icorr); three sets of parallel samples were used, and the results are expressed as mean ± standard deviation.

[0129] Corrosion morphology observation: After the corrosion sample is immersed in 3.5 wt% NaCl aqueous solution for 1000 hours, observe whether corrosion pits, corrosion points or other corrosion morphologies appear on the surface.

[0130] The test results are shown in Tables 1 and 2.

[0131] Table 1. Test results of cemented carbide properties

[0132] Hardness HRA Fracture toughness KIC (MPa·m¹ / ²) Self-corrosion potential Ecorr (V vs SCE) Corrosion current density Icorr (μA / cm²) Example 1 92.8±0.3 11.6±0.4 -0.18±0.02 1.95±0.15 Example 2 92.1±0.3 12.3±0.5 -0.22±0.03 2.85±0.20 Example 3 93.0±0.2 10.7±0.4 -0.15±0.02 1.60±0.12 Comparative Example 1 90.2±0.4 11.0±0.4 -0.42±0.04 14.80±1.20 Comparative Example 2 91.8±0.3 10.5±0.6 -0.25±0.03 3.85±0.30 Comparative Example 3 92.5±0.2 10.4±0.5 -0.21±0.02 2.75±0.18 Comparative Example 4 91.6±0.4 10.8±0.6 -0.30±0.03 6.50±0.50 Blank Group 1 88.6±0.5 10.1±0.6 -0.48±0.05 18.50±2.10 Blank Group 2 89.2±0.3 13.8±0.4 -0.38 ± 0.03 8.25 ± 0.80 Blank Group 3 87.0±0.4 14.2±0.5 -0.32 ± 0.03 5.80±1.20

[0133] Table 2 Observation results of corrosion morphology

[0134] Corrosion morphology Example 1 The surface is smooth and intact, with no visible corrosion pits or spots. Example 2 The surface is smooth and intact, with no visible corrosion pits or spots. Example 3 The surface is smooth and intact, with no visible corrosion pits or spots. Comparative Example 1 Corrosion pits are visible on the surface. Comparative Example 2 Corrosion pits are visible on the surface. Comparative Example 3 Corrosion pits are visible on the surface. Comparative Example 4 Visible corrosion spots on the surface Blank Group 1 Corrosion pits are visible on the surface. Blank Group 2 Corrosion pits are visible on the surface. Blank Group 3 Corrosion pits are visible on the surface.

[0135] As shown in Tables 1 and 2, this invention achieves a good balance of hardness, toughness, and corrosion resistance while reducing the amount of WC used. It maintains high hardness and high toughness while exhibiting high corrosion resistance, making it suitable for applications in deep-sea corrosion-resistant components.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A low-carbide tungsten carbide cemented carbide with an NbC lattice framework-dominated structure, characterized in that: The material is prepared from the following raw materials, which include hard phase raw materials, binder phase raw materials, and modifiers; The hard phase raw materials include niobium carbide and tungsten carbide; niobium carbide accounts for 82-96 wt% of the total mass of the hard phase raw materials, and the C / Nb atomic ratio of niobium carbide is 0.96-1.04; tungsten carbide accounts for 4-18% of the total mass of the hard phase raw materials. The binder phase raw materials include a polyboron silazane / boron phosphate hybrid network precursor and a Co-Ni binary alloy; The regulators include a Cr3C2 / Mo2C mixture, a magnesium-aluminum bimetallic hydroxide / Si3N4 complex, and borazine-modified boron nitride nanofibers.

2. The NbC lattice framework-dominated low-carbide tungsten carbide according to claim 1, characterized in that: The polyborosilicate / boron phosphate hybrid network precursor is prepared by the following method: The polyborosilicate precursor is dissolved in xylene to prepare a polyborosilicate precursor solution with a mass concentration of 15%–25%; boron phosphate is added to the polyborosilicate precursor solution at an amount of 2%–2.5% of the mass of the polyborosilicate precursor, and the solution is ultrasonically dispersed to obtain a uniform dispersion; under a nitrogen or argon atmosphere, a triethylamine / 4-dimethylaminopyridine dual catalyst is added to the dispersion, and the mixture is stirred at 60°C for 3–4 hours. After the reaction is complete, the mixture is distilled under reduced pressure to obtain the polyborosilicate / boron phosphate hybrid network precursor; wherein the amount of triethylamine added is 2 wt% of the mass of the polyborosilicate precursor, and the amount of 4-dimethylaminopyridine added is 1 wt% of the mass of the polyborosilicate precursor. The amount of the polyborosilazane / boron phosphate hybrid network precursor added is 10% of the total mass of the hard phase feedstock.

3. The NbC lattice framework-dominated low-carbide tungsten carbide according to claim 1, characterized in that: The mass ratio of Co to Ni in the Co-Ni binary alloy is 1:1; the amount of Co-Ni binary alloy added is 3wt% of the total mass of the hard phase raw materials.

4. The NbC lattice framework-dominated low-carbide tungsten carbide according to claim 1, characterized in that: The mass ratio of Cr3C2 to Mo2C in the Cr3C2 / Mo2C mixture is 2:1; the amount of Cr3C2 / Mo2C mixture added is 0.25% of the total mass of the hard phase raw material and the binder phase raw material.

5. The NbC lattice framework-dominated low-carbide tungsten carbide according to claim 1, characterized in that: The magnesium-aluminum bimetallic hydroxide / Si3N4 composite was prepared by the following method: magnesium nitrate and aluminum nitrate were dissolved in deionized water at a Mg:Al molar ratio of 2:1 to prepare a mixed salt solution with a concentration of 0.5 mol / L; the mixed salt solution was added dropwise to an ethanol suspension of Si3N4 under stirring; after the addition was completed, dilute ammonia was added dropwise to the reaction system to adjust the pH to 9.5; the reaction was carried out at 60°C for 12 hours; after the reaction was completed, the mixture was centrifuged, washed, and dried to obtain the magnesium-aluminum bimetallic hydroxide / Si3N4 composite. The amount of magnesium-aluminum bimetallic hydroxide / Si3N4 composite added is 1% of the total mass of the hard phase raw material and the binder phase raw material.

6. The NbC lattice framework-dominated low-carbide tungsten carbide according to claim 1, characterized in that: The borazine-modified boron nitride nanofibers were prepared by the following method: Boron nitride nanofibers were placed in a low-temperature oxygen plasma treatment device and treated for 5 minutes under an oxygen atmosphere and a power of 200 W to obtain pretreated boron nitride nanofibers; under an inert atmosphere, the pretreated boron nitride nanofibers, borazine, and triethylamine were added to a reaction vessel and sealed for reaction. The borazine accounted for 30 wt% of the mass of the pretreated boron nitride nanofibers, and the amount of triethylamine added was 2 wt% of the mass of the pretreated boron nitride nanofibers; under a sealed container, the mixture was ultrasonically treated at 35-45℃ for 30 minutes, then heated to 50℃ and held for 3-4 hours. After the reaction, the temperature was raised to 120℃ and stirred for 2-3 hours. After the reaction, the mixture was centrifuged, the precipitate was collected, washed, vacuum dried, and then heat-treated at 200℃ for 2 hours under an inert gas protection at a rate of 2-5℃ / min to obtain borazine-modified boron nitride nanofibers. The amount of boron azazine-modified boron nitride nanofibers added is 1.2% of the total mass of the hard phase raw material and the binder phase raw material.

7. A method for preparing an NbC lattice framework-dominated low-carbide tungsten carbide according to any one of claims 1-6, characterized in that: Includes the following steps: S1. Niobium carbide and tungsten carbide are mixed evenly and placed in a radio frequency plasma treatment device. Surface activation treatment is carried out in an atmosphere of H2 and Ar with a volume ratio of 1:

8. The radio frequency power is 300W and the treatment time is 30 minutes to obtain a hard phase raw material. S2. Place the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture in a three-dimensional vibrating ball mill, add 1% stearic acid of the total mass of the hard phase raw material, Co-Ni binary alloy, and Cr3C2 / Mo2C mixture, with a ball-to-material ratio of 5:1 and a rotation speed of 150-200 rpm. Add magnesium-aluminum bimetallic hydroxide / Si3N4 composite 30 min before the end of ball milling, and ball mill for 8 h. After ball milling, vacuum dry at 60℃ for 6 h to obtain composite powder. S3. Dissolve the polyborosilicate / boron phosphate hybrid network precursor in xylene to form a solution with a mass concentration of 15-25%. Under stirring, add the composite powder and boron azine-modified boron nitride nanofibers to the solution in sequence. After stirring evenly, a composite slurry is obtained. S4. After vacuum drying of the composite slurry at 80-120℃, it is cold isostatically pressed at 200-300 MPa for 5-10 minutes to obtain the green body. S5. Perform three-stage vacuum sintering on the green body: First stage: Increase the temperature to 150-250℃ at a rate of 1-2℃ / min, hold for 60-120 minutes, and maintain a vacuum level better than 10. -2 Pa; Second stage: After the first stage of heat preservation, increase the temperature to 1000-1150℃ at a rate of 2-4℃ / min, and maintain the temperature for 60-90 minutes, with a vacuum degree better than 10. -2 Pa; Third stage: After the second stage of heat preservation, increase the temperature to 1300-1400℃ at a rate of 1-2℃ / min, and hold for 30-60 minutes, with a vacuum degree better than 10. -2 Pa; S6. Post-treatment: After the third stage of sintering is completed, argon gas is introduced to increase the pressure to 80-150MPa within the temperature range of 1250-1350℃, and the pressure is maintained for 0.5-2 hours. S7, Gradient Cooling Rapid cooling section: After post-treatment, cool to 1000-1050℃ at 15-25℃ / min; Medium-temperature insulation section: After rapid cooling, cool to 750-850 ℃ at 3-5 ℃ / min, and maintain the temperature for 20-40 min; Slow cooling section: After holding at medium temperature, the material is cooled to room temperature at a rate of less than 2 °C / min to obtain a low-carbide tungsten carbide with an NbC lattice framework.

8. The application of the NbC lattice framework-dominated low-carbide tungsten carbide according to any one of claims 1-6, characterized in that: The aforementioned NbC lattice framework-dominant low-carbide tungsten carbide is used to prepare deep-sea wear-resistant and corrosion-resistant components.

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