A cemented carbide nozzle for jet abrasives and its preparation method

Abstract

This invention belongs to the field of high-pressure jet cutting nozzle manufacturing technology, specifically relating to a cemented carbide for jet abrasive nozzles and its preparation method. The cemented carbide for jet abrasive nozzles includes a cemented carbide matrix and a boride coating. The composition of the cemented carbide matrix is: 1wt%~3wt% cobalt, 3wt%~12wt% molybdenum carbide, 3wt%~10wt% tantalum carbide, 1wt%~3wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.2~0.6μm. This invention prepares a high-strength and tough cemented carbide matrix by using a low-cobalt ultrafine-grained cemented carbide with a specific composition and a gas pressure sintering process. Then, a TiB2 superhard coating with a strong (001) texture is deposited on its surface by a controllable chemical vapor deposition technology, achieving a unity of ultra-high coating hardness and extremely high interfacial bonding force, and finally obtaining a jet abrasive nozzle composite material with excellent wear resistance, long service life, and stable performance.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure jet cutting nozzle manufacturing technology, specifically a cemented carbide for jet abrasive nozzles and its preparation method. Background Technology

[0002] The working principle of a high-pressure jet nozzle is to use an ultra-high-pressure booster to gradually increase the pressure of the liquid to 200~400MPa, and then pass it through a nozzle with a diameter of less than 0.2mm to form a jet with a velocity of up to 1000m / s, creating a high-kinetic-energy jet that is sprayed onto the surface of the workpiece and destroys it. When water-jet cutting is combined with abrasives such as quartz sand, alumina, and corundum, the cutting force is greatly improved, making it suitable for cutting almost any hard material.

[0003] Due to the demanding operating requirements of high-pressure jet nozzles, the performance requirements for nozzle materials are extremely high. These materials must possess extremely high relative density, be free of defects such as pores and cracks, and exhibit excellent wear resistance and corrosion resistance. Therefore, binderless cemented carbides, which offer superior wear resistance, corrosion resistance, and excellent polishability compared to traditional cemented carbides, are typically used as nozzle materials. However, tungsten carbide is a high-melting-point carbide (2870℃), and without a binder phase, it is difficult to obtain a dense binderless cemented carbide using traditional sintering methods, leading to a sharp reduction in product lifespan. Dense nanocrystalline cemented carbide blocks are typically prepared using hot isostatic pressing or SPS rapid sintering, followed by cutting, drilling, and dimensional finishing. However, this process suffers from high processing costs and a high scrap rate. Meanwhile, using WC-Co cemented carbide as a raw material offers a cost advantage due to molding, but the presence of cobalt results in lower hardness and poor corrosion resistance, leading to a shorter lifespan as a jet nozzle material, limiting its application to conditions with lower lifespan requirements. Therefore, it is urgent to further improve the service life of jet nozzles and reduce their production costs. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a cemented carbide for jet abrasive nozzles, comprising a cemented carbide substrate and a boride coating; The composition of the cemented carbide matrix is: 1wt%~3wt% cobalt, 3wt%~12wt% molybdenum carbide, 3wt%~10wt% tantalum carbide, 1wt%~3wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities, wherein the average grain size of the tungsten carbide is 0.2~0.6μm; The boride coating has a preferred orientation of the (001) plane with an orientation degree greater than or equal to 2.5.

[0005] Furthermore, the average grain size of the tungsten carbide is any one of 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, or a range between two of them.

[0006] Wherein, the molybdenum carbide is β-Mo2C, and the crystal structures of both the tungsten carbide and the molybdenum carbide are hexagonal close-packed structures, and the tungsten carbide and the molybdenum carbide form a solid solution structure in the cemented carbide matrix.

[0007] The boride coating is a TiB2 coating with a close-packed hexagonal crystal structure and a thickness of 1~5μm.

[0008] Furthermore, the thickness of the boride coating is any one of 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or a range between two of them.

[0009] The cemented carbide matrix conforms to the standard GB / T3488.4-2022, which specifies a porosity of A00B00, a non-combined carbon structure of C00, and a decarburized phase of E00.

[0010] The Vickers hardness of the cemented carbide matrix is ​​greater than or equal to 2550 HV.

[0011] The boride coating has a Vickers hardness of 4000 HV or greater, and the critical load of the interfacial bonding force between the boride coating and the cemented carbide substrate is 80 N or greater.

[0012] To address the aforementioned technical problems, the present invention also provides a method for preparing a cemented carbide for jet abrasive nozzles, comprising the following steps: S1. Obtain raw materials based on the composition of the cemented carbide matrix; S2. The raw materials and molding agent are mixed and then wet ball-milled, followed by spray drying to obtain spherical composite powder; S3. The spherical composite powder is molded into a green body; S4. The green blank is degreased, and then subjected to gas pressure sintering at a temperature of 1550~1650℃ and a nitrogen pressure of 10~20MPa. After cooling at a cooling rate of 25~40℃ / min, a cemented carbide matrix is ​​obtained. S5. After end face grinding and internal hole finishing of the cemented carbide substrate, a boride coating is deposited on the surface of the cemented carbide substrate by chemical vapor deposition.

[0013] Furthermore, the temperature for gas pressure sintering is any one of 1550℃, 1600℃, 1650℃, or a range between two of them.

[0014] Furthermore, the nitrogen pressure for gas pressure sintering is any one of 10MPa, 12MPa, 14MPa, 16MPa, 18MPa, 20MPa, or a range between two of them.

[0015] Furthermore, the cooling rate is any one of 25°C / min, 30°C / min, 35°C / min, 40°C / min, or a range between two of them.

[0016] In step S2, the molding agent is paraffin or PEG, and its mass is equivalent to 0% to 4% of the raw material. The ball milling medium for the wet ball milling is water or alcohol, and the time is 12 to 70 hours.

[0017] In step S4, the degreasing process involves degreasing the green body at a temperature of 150-500°C under a protective gas atmosphere.

[0018] In step S5, the boride coating is a TiB2 coating. The gas mixture of the chemical vapor deposition method consists of 0.9 vol% to 1.2 vol% BCl3, 0.2 vol% to 0.7 vol% TiCl4, and the balance H2. The deposition temperature is 700 to 900℃, the deposition pressure is 30 to 200 mbar, and the molar ratio of BCl3 to TiCl4 is controlled to be 2.6 to 4.2 to induce the TiB2 coating to preferentially grow along the (001) direction.

[0019] Furthermore, the deposition temperature is any one of 700°C, 750°C, 800°C, 850°C, 900°C, or a range between two of them.

[0020] Furthermore, the deposition pressure is any one of 30 mbar, 50 mbar, 70 mbar, 90 mbar, 110 mbar, 130 mbar, 150 mbar, 170 mbar, 190 mbar, 200 mbar, or a range between two of them.

[0021] This invention prepares a high-strength and tough cemented carbide matrix by using a low-cobalt ultrafine-grained cemented carbide with specific composition design and a gas pressure sintering process. Then, a TiB2 superhard coating with a strong (001) texture is deposited on its surface by a controllable chemical vapor deposition technology. By utilizing crystal structure matching and thermal stress buffering design, the ultra-high hardness of the coating and the extremely high interfacial bonding force are achieved. Finally, a jet abrasive nozzle composite material with excellent wear resistance, long service life and stable performance is obtained. Moreover, the entire preparation method is mature, controllable and low-cost, and suitable for industrial production. Detailed Implementation

[0022] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a cemented carbide for jet abrasive nozzles, comprising a cemented carbide substrate and a boride coating; The composition of the cemented carbide matrix is: 1wt%~3wt% cobalt, 3wt%~12wt% molybdenum carbide, 3wt%~10wt% tantalum carbide, 1wt%~3wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities, wherein the average grain size of the tungsten carbide is 0.2~0.6μm; The boride coating has a preferred orientation of the (001) plane with an orientation degree greater than or equal to 2.5.

[0024] The cemented carbide matrix in this invention is a high-strength and high-toughness cemented carbide matrix. It combines ultrafine-grained tungsten carbide (0.2~0.6μm) with low cobalt content (1wt%~3wt%), and adds molybdenum carbide (3wt%~12wt%), tantalum carbide (3wt%~10wt%), and chromium carbide (1wt%~3wt%). Under pressure sintering (1550~1650℃, 10~20MPa nitrogen), a matrix with excellent metallographic properties (meeting the standards of porosity A00B00, non-combined carbon structure C00, and decarburized phase E00 in GB / T3488.4-2022), high hardness (greater than or equal to 2550HV) and dense structure is obtained. The low cobalt content and ultrafine-grained tungsten carbide structure ensure the high hardness and good toughness of the matrix, providing a solid support for the coating.

[0025] The coating in this invention is an ultra-hard coating that is firmly bonded to the cemented carbide substrate. The TiB2 coating prepared by chemical vapor deposition (CVD) has extremely high hardness (greater than or equal to 4000 HV). By controlling the deposition parameters (especially controlling the molar ratio of BCl3 and TiCl4 to 2.6~4.2), the coating exhibits a strong (001) plane preferred orientation (orientation degree greater than or equal to 2.5). This orientation achieves crystallographic matching with the main matrix components (WC, β-Mo2C solid solution), which are also hexagonal in structure.

[0026] In this invention, molybdenum carbide (β-Mo2C) forms a close-packed hexagonal solid solution with tungsten carbide, which is compatible with the TiB2 coating structure and promotes bonding; tantalum carbide (with a coefficient of thermal expansion of (…) The addition of tungsten carbide balances its coefficient of thermal expansion (CPE). ) and molybdenum carbide (coefficient of thermal expansion) ) and TiB2 coating (coefficient of thermal expansion) The large difference in thermal expansion coefficients makes the critical load of the interfacial bonding force between the coating and the substrate reach more than 80N; trace amounts of chromium carbide (1wt%~3wt%) can further improve sinterability and wear resistance. The synergistic effect of these components is the basis for achieving high comprehensive performance.

[0027] This invention effectively suppresses grain growth by combining gas pressure sintering with rapid cooling, ensuring a dense substrate with few defects. Precise control of gas ratio, temperature (700~900℃), and pressure (30~200mbar) in chemical vapor deposition is a direct guarantee for obtaining a coating with predetermined orientation, high hardness, and uniform thickness (1~5μm).

[0028] Example 1 A method for preparing a cemented carbide nozzle for jet abrasives includes the following steps: S1. Obtain raw materials, which include: 1.8 wt% cobalt powder, 5 wt% β-molybdenum carbide powder, 6 wt% tantalum carbide powder, 1.5 wt% chromium carbide, with the balance being tungsten carbide powder and unavoidable impurities, wherein the average Fisher particle size of the tungsten carbide powder is 0.3 μm. S2. The raw materials and molding agent are mixed and then wet ball-milled, followed by spray drying to obtain spherical composite powder. The molding agent is PEG, which is equivalent to 2% of the raw materials by mass. The ball milling medium for wet ball milling is alcohol, and the time is 35 hours. S3. The spherical composite powder is molded into a green body, and the molding pressure is 2.0 t / cm. 2 ; S4. The green blank is degreased at 350°C and in a nitrogen atmosphere, then subjected to gas pressure sintering at 1600°C and 20MPa nitrogen pressure, and cooled at a cooling rate of 30°C / min to obtain a cemented carbide matrix. S5. After end face grinding and internal hole finishing of the cemented carbide substrate, a boride coating is deposited on the surface of the cemented carbide substrate by chemical vapor deposition. The gas mixture for chemical vapor deposition consists of 1.12 vol% BCl3, 0.35 vol% TiCl4, and the balance H2. The deposition temperature is 800℃, the deposition pressure is 100 mbar, and the molar ratio of BCl3 to TiCl4 is controlled to be 3.2 to induce the TiB2 coating to preferentially grow along the (001) direction. The thickness of the boride coating is 3 μm, and the boride coating has a preferred orientation of the (001) plane with an orientation degree of 3.1.

[0029] The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2600 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4112 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 88 N.

[0030] Example 2 Unlike Example 1, in step S1, the cobalt powder content in the raw material is 1.1 wt%; in step S5, the thickness of the boride coating is 1.5 μm.

[0031] The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 1.1 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2650 HV. The boride coating is a TiB2 coating with a thickness of 1.5 μm and a Vickers hardness of 4112 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 89 N.

[0032] Example 3 Unlike Example 1, in step S1, the cobalt powder content in the raw material is 2.8 wt%; in step S5, the thickness of the boride coating is 4.5 μm.

[0033] The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 2.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2550 HV. The boride coating is a TiB2 coating with a thickness of 4.5 μm and a Vickers hardness of 4112 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 86 N.

[0034] Example 4 Unlike Example 1, the average Fisher particle size of the tungsten carbide powder in step S1 is 0.5 μm; The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.5 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2570 HV. The boride coating is a TiB2 coating with a Vickers hardness of 4112 HV, and the critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 88 N.

[0035] Example 5 Unlike Example 1, in step S5, the gas mixture for chemical vapor deposition consists of 0.91 vol% BCl3, 0.35 vol% TiCl4, and the balance H2. The molar ratio of BCl3 to TiCl4 is controlled to be 2.6 to induce the TiB2 coating to preferentially grow along the (001) direction. The boride coating has a preferred orientation of the (001) plane with an orientation degree of 2.5. The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity of A00B00, non-combined carbon structure of C00, and decarburized phase of E00, and has a Vickers hardness of 2600 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4080 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 83 N.

[0036] Example 6 Unlike Example 1, in step S5, the gas mixture for chemical vapor deposition consists of 1.176 vol% BCl3, 0.28 vol% TiCl4, and the balance H2. The molar ratio of BCl3 to TiCl4 is controlled to be 4.2 to induce the TiB2 coating to preferentially grow along the (001) direction. The boride coating has a preferred orientation of the (001) plane with an orientation degree of 2.6. The cemented carbide for jet abrasive nozzles prepared in this embodiment includes a cemented carbide substrate and a boride coating. The cemented carbide substrate is composed of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2600 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4150 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 86 N.

[0037] Comparative Example 1 Unlike Example 1, step S5 does not include a coating step; The prepared cemented carbide for jet abrasive nozzles includes a cemented carbide matrix, the composition of which is: 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide matrix conforms to the standard of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00. The Vickers hardness is 2600 HV.

[0038] Comparative Example 2 Unlike Example 1, the cemented carbide matrix was prepared by hot pressing and sintering. The specific differences from Example 1 are as follows: In step S1, the raw materials include: 0.35 wt% cobalt powder, 1.2 wt% chromium carbide, the balance being tungsten carbide powder and unavoidable impurities, wherein the average Fisher particle size of the tungsten carbide powder is 0.3 μm; step S3 is to dry and granulate the spherical composite powder to obtain hot-pressed powder; step S4 is to place the hot-pressed powder in a graphite mold and then perform hot-pressing sintering in a hot-pressing sintering furnace, wherein the initial axial pressure of the hot-pressing sintering is 7 MPa, the vacuum is drawn to a pressure less than 5 Pa, the heating rate is 15 °C / min, when the temperature reaches 1700 °C, the axial pressure is increased to 30 MPa, the sintering temperature is 1700 °C, the sintering time is 40 min, and the furnace is cooled to obtain a cemented carbide matrix, which is then cut into the same shape as in Example 1; The prepared cemented carbide for jet abrasive nozzles has the following composition: 0.35 wt% cobalt, 1.2 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide matrix conforms to the standard of GB / T3488.4-2022, which specifies porosity of A00B00, non-combined carbon structure of C00, and decarburized phase of E00. The Vickers hardness is 2900 HV.

[0039] Comparative Example 3 Unlike Example 1, in step S1, no tantalum carbide powder was added. The raw materials included: 2.8 wt% cobalt powder, 5 wt% β-molybdenum carbide powder, 1.5 wt% chromium carbide, and the balance being tungsten carbide powder and unavoidable impurities. The average Fisher particle size of the tungsten carbide powder was 0.3 μm. The prepared cemented carbide for jet abrasive nozzles comprises a cemented carbide substrate and a boride coating. The cemented carbide substrate consists of 2.8 wt% cobalt, 1.5 wt% chromium carbide, 5 wt% β-molybdenum carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2680 HV. The boride coating is a TiB2 coating with a Vickers hardness of 4012 HV, and the critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 66 N.

[0040] Comparative Example 4 Unlike Example 1, in step S1, the cobalt powder content in the raw material is 6.0 wt%, with the remainder being tungsten carbide powder and unavoidable impurities; The prepared cemented carbide for jet abrasive nozzles comprises a cemented carbide substrate and a boride coating. The cemented carbide substrate consists of 6.0 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity of A00B00, non-combined carbon structure of C00, and decarburized phase of E00, and has a Vickers hardness of 2000 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4012 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 60 N.

[0041] Comparative Example 5 Unlike Example 1, in step S1, β-molybdenum carbide powder was not added, and the raw materials included: 1.8 wt% cobalt powder, 6 wt% tantalum carbide powder, 1.5 wt% chromium carbide powder, with the balance being tungsten carbide powder and unavoidable impurities. The prepared cemented carbide for jet abrasive nozzles comprises a cemented carbide substrate and a boride coating. The cemented carbide substrate consists of 1.8 wt% cobalt, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity of A00B00, non-combined carbon structure of C00, and decarburized phase of E00, and has a Vickers hardness of 2580 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 3900 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 50 N.

[0042] Comparative Example 6 Unlike Example 1, in step S1, the average Fisher particle size of the tungsten carbide powder is 1.5 μm; The prepared cemented carbide for jet abrasive nozzles comprises a cemented carbide substrate and a boride coating. The cemented carbide substrate consists of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 1.5 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity as A00B00, non-combined carbon structure as C00, and decarburized phase as E00, and has a Vickers hardness of 2200 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4012 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 85 N.

[0043] Comparative Example 7 Unlike Example 1, in step S5, the molar ratio of BCl3 to TiCl4 in the chemical vapor deposition gas mixture is controlled to be 1.5, the deposition temperature is 800°C, the deposition pressure is 100 mbar, and the boride coating has a preferred orientation of (001) plane with an orientation degree of 1.2. The prepared cemented carbide for jet abrasive nozzles comprises a cemented carbide substrate and a boride coating. The cemented carbide substrate consists of 1.8 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide substrate conforms to the standards of GB / T3488.4-2022, which specifies porosity of A00B00, non-combined carbon structure of C00, and decarburized phase of E00, and has a Vickers hardness of 2600 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 3600 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is 45 N.

[0044] Comparative Example 8 Unlike Example 1, in step S1, the cobalt powder content in the raw material is 0.35 wt%. The prepared cemented carbide for jet abrasive nozzles comprises a matrix of 0.35 wt% cobalt, 5 wt% molybdenum carbide, 6 wt% tantalum carbide, 1.5 wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.3 μm. The porosity of the cemented carbide matrix conforms to the standard of A02B04 porosity in GB / T3488.4-2022, and the Vickers hardness is 2850 HV. The boride coating is a TiB2 coating with a thickness of 3.0 μm and a Vickers hardness of 4112 HV. The critical load for the interfacial bonding force between the boride coating and the cemented carbide matrix is ​​78 N.

[0045] The following are nozzle performance tests: The jet abrasive nozzles prepared in the above embodiments and comparative examples were installed in a commercial waterjet system (working pressure set at 420MPa) and continuously cut a 20mm thick 304 stainless steel standard test plate. The service life of the embodiments of the present invention was greater than or equal to 340h under the test conditions.

[0046] During the experiment, the service life of each jet abrasive nozzle was recorded; service life refers to the cumulative cutting time (h) from the start of cutting until the cut perpendicularity error exceeds 0.1mm, or the cutting speed drops to 80% of the initial speed.

[0047] The specific test results are shown in Table 1.

[0048] Table 1 This invention prepares a high-strength and tough cemented carbide matrix by using a low-cobalt ultrafine-grained cemented carbide with specific composition design and a gas pressure sintering process. Then, a TiB2 superhard coating with a strong (001) texture is deposited on its surface by a controllable chemical vapor deposition technology. By utilizing crystal structure matching and thermal stress buffering design, the ultra-high hardness of the coating and the extremely high interfacial bonding force are achieved. Finally, a jet abrasive nozzle composite material with excellent wear resistance, long service life and stable performance is obtained. Moreover, the entire preparation method is mature, controllable and low-cost, and suitable for industrial production.

[0049] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cemented carbide for a fluid abrasive jet nozzle, characterized in that, Includes a cemented carbide substrate and a boride coating; The composition of the cemented carbide matrix is: 1wt%~3wt% cobalt, 3wt%~12wt% molybdenum carbide, 3wt%~10wt% tantalum carbide, 1wt%~3wt% chromium carbide, with the balance being tungsten carbide and unavoidable impurities. The average grain size of the tungsten carbide is 0.2~0.6μm; the molybdenum carbide is β-Mo2C; both the tungsten carbide and the molybdenum carbide have a close-packed hexagonal crystal structure. The boride coating has a preferred orientation of the (001) plane with an orientation degree greater than or equal to 2.5; the boride coating is a TiB2 coating with a close-packed hexagonal crystal structure. The critical load for the interfacial bonding force between the boride coating and the cemented carbide substrate is greater than or equal to 80 N.

2. The cemented carbide for a fluid abrasive jet nozzle according to claim 1, wherein The tungsten carbide and the molybdenum carbide form a solid solution structure in the cemented carbide matrix.

3. The cemented carbide nozzle for jet abrasives according to claim 1, characterized in that, The thickness of the boride coating is 1~5μm.

4. The cemented carbide nozzle for jet abrasives according to claim 1, characterized in that, The cemented carbide matrix conforms to the standard of GB / T3488.4-2022, which specifies a porosity of A00B00, a non-combined carbon structure of C00, and a decarburized phase of E00.

5. The cemented carbide nozzle for jet abrasives according to claim 1, characterized in that, The Vickers hardness of the cemented carbide matrix is ​​greater than or equal to 2550 HV.

6. The cemented carbide nozzle for jet abrasives according to claim 1, characterized in that, The Vickers hardness of the boride coating is greater than or equal to 4000 HV.

7. A method for preparing a cemented carbide for jet abrasive nozzles, used to prepare the cemented carbide for jet abrasive nozzles according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Obtain raw materials based on the composition of the cemented carbide matrix; S2. The raw materials and molding agent are mixed and then wet ball-milled, followed by spray drying to obtain spherical composite powder; S3. The spherical composite powder is molded into a green body; S4. The green blank is degreased, and then subjected to gas pressure sintering at a temperature of 1550~1650℃ and a nitrogen pressure of 10~20MPa. After cooling at a cooling rate of 25~40℃ / min, a cemented carbide matrix is ​​obtained. S5. After end face grinding and internal hole finishing of the cemented carbide substrate, a boride coating is deposited on the surface of the cemented carbide substrate by chemical vapor deposition.

8. A method for preparing a cemented carbide nozzle for jet abrasives according to claim 7, characterized in that, In step S2, the molding agent is paraffin or PEG, and its mass is equivalent to 0% to 4% of the raw material. The ball milling medium for the wet ball milling is water or alcohol, and the time is 12 to 70 hours.

9. A method for preparing a cemented carbide nozzle for jet abrasives according to claim 7, characterized in that, In step S4, the degreasing is performed by degreasing the green blank at a temperature of 150~500℃ and under a protective gas atmosphere.

10. A method for preparing a cemented carbide nozzle for jet abrasives according to claim 7, characterized in that, In step S5, the boride coating is a TiB2 coating. The gas mixture of the chemical vapor deposition method consists of 0.9 vol%~1.2 vol% BCl3, 0.2 vol%~0.7 vol% TiCl4, and the balance H2. The deposition temperature is 700~900℃, the deposition pressure is 30~200 mbar, and the molar ratio of BCl3 to TiCl4 is controlled to be 2.6~4.2 to induce the TiB2 coating to preferentially grow along the (001) direction.

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